Block-signal system.



L; A. HAWKINS.

BLOCK SIGNAL SYSTEM.

APPLICATION IILED JUNE 10, 1907. RENEWED APR. 28, 1 909.

937,738. Patented Oct. 19,1909.

i J L W1TNE55E5= INVENTDR q LAURENEEAHAWKINE,

LAURENCE A. HAWKINS, F

SCI'IENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

BLOCK-SIGNAL SYSTEM.

Specification of Letters Patent.

Application filed June 10, 1907, Serial No. 378,243. Renewed April 28, 1909. Serial No. 492,769.

To all whom it may concern:

Be it known that I, LAURENCE A. HAW- runs, a citizen of the United States, residing at Schenectady, county of Schenectady,

State of New York, have invented certain new and useful Improvements in Block-Signal Systems, of which the following is a specification.

My invention relates to block signal sys- 1 tems for electric railways, and consists inan improvement in the system described in my former application, Serial No. 3293M, filed August 6, i906. In that former application I described a signalsystem in which both rails are con ductivcly continuous for all currents, and sources of current are connected across the rails at the ends of the blocks, the currents from adjacent sources being of different frequency. are connected in pairs across the rails at points between the sources, each relay responding only to current of one frequency.

The two relays jointly control a signal for the portion of the track between the sources, so that when either source is cut oil' from the relays bya train in the block the signal goes to danger. Since the rails in the system are continuous, an approaching train begins to lower the voltage supplied to the rails by the transformer atthe entrance of the block before the train reaches that transformer, so

that the relay responding to the current from that source dropsits contact before the train reaches the transformer. In order to make the length of the block definite, orin other words, to make more or less definite the 'point reached by the train when the signal goes to danger, I- took advantage in the system of my earlier application ofthe high impedance of an iron rail to alternatin currents of high frequency.

By using higli frequency currents and transformers of fairly for-the current sources, the so arranged that the signal will not go to danger until the train is close to the trans-former. In my former application, I suggested 250 and 300 cycles as suitable frequencies.

For railways having very long blocks, a high'freque'ncy signal current is disadvan tageous, since it necessitates employing a high voltage for the signal current with consequent leakage. My present invention consists in providing means for making the entrance end of Track relays E the block absolutely fixed, so that currents of low frequency may be used forthe signal circuits, if desired. 1 accomplish this result by providing a magnet cooperating with the track relays to control the signal and arranged to be actuated only when a train reaches a fixed point. This magnet may control contacts shunting the contacts of the relay supplied from the transformer at the entrance of the block. -\Vith this arrangement, the relay supplied from that transformer may drop ,its'contacts without putting the signal at danger. The signal reniains at clear until the train reaches the fixed'point. \Vith the arrangement above outlined, it will be seen that if a train approaches a signal of an occupied block, finds it at danger, and stops in' front of the signal, its presence will prevent the track relay suplied from the transformer at the entrance end' of the block from picking up its contacts when the block is again clear, and consequently will prevent the signal from clearing. While this is not'always objectionable, since in automatic signal systems it is usually the rule for a train on finding a signal at danger to wait a certain length" of time and I prefer to arrange the system so that the signal will clear at on'ce when the train ahead leaves ,the' block; and a second feature of my invention consists in the arrangement for doing this. I accomplish the desired result, as will be hereinafter explained, by controlling the relay supplied from the transformer at the entrance of theblock by the relay responding to the current from the transformer at the exit end of the block. \Vhile this second feature of my invention is particularly advantageous for use in connection with the first feature, it may also be used to advantage in certain cases in the system described in my former application, Without the use of the first feature. The reason for this is that it frequently is desirable to design the relay so that its torque, withits contacts closed, is'greater than with its contacts open, in order to make the operation of he relay more positive. Even if the relay is not intentionally designed to secure this result, this characteritic, due to its inertia and friction. .Consequently, if the signal is placed ata pointwhere the train shunts the the relay may often possess Patented Oct. 19, 1909.

. relay supplied from the transformer at the less a little time might occasionally-be lost,

. invention.

entrance end of the blocks'ufliciently to make it drop its contacts, then if'the relay contacts are once down, as would be the case. Wllil'l a train in the block, and if a second train stands at the signal waiting for it to clear, the relay will not pick u when'the first train leaves the block. hile this is not highly objectionable with the rule ordinarily in force,jmentioned above, neverthewhich can besaved by supplying to the system what I have termed the second feature of my present invention. I

My invention will best beunderstood by reference to the accompanying drawing,

which shows diagrammatically a block sig-- accordance with my.

nal system arranged in nal of this generator may be connected to the wlnding f v one of the transformers.

shown relays I ing the relay windings f rails through a differential choke-coil 0,,so

that the rails .act as return conductor for the power-current.

' D and 'D re resent alternating current generators of di erent frequencies connected to the line-wires d, d and 0Z line-wire d serving as common return for currents of both frequencies. E and E represent transformers having their primaries connected to the line-wires, and their secondaries to the track. Adjacent transformers are connected to line-wires carrying currents of different frequencies.

I and F represent a pair of track relays approximately midway between the transformers'EF and E While current from both transformers passes throughthe track windings of the two relays, each relay is arranged to respond to current from only Thus, relay F may respond only to current from/transformer E and relay F only to current from transformer E In order to makethe relays thusselective, they are supplied with two cooperating windings, one connected across the track, and theother supplied with current independently of, the tracln I have of the well known induction type, comprising a short-circuiting member f carrying the relay contacts, a primary connected across the track, the track windings of the two relays being I shown connected in series, and a winding 2 supplied independently of the track with current of the same frequency as,but of different phase from, that supplied by one of the transformers E and'E I have .shown transformers G and G with their primaries contacts of relay F tacts,

For supplyconnected to the line-wires and their sec ondaries connected 'to' the relay windings. 1

Phase-controlling devices 9 may be employed to secure the necessary phase-difference between the currents in the two windings of the relay. This phase-difference should be approximately 90 degrees for maximum torque. .The .two relays F and F jointly control a signal H," the operating mechanism of which is indicated diagram-. m'atically'at hand its source of current The system, same as that disclosed in my former application, above referred to.

I represents a magnet, one terminal of which is connected to the lower rail A, and the other terminal of which is connected as thus far described, is the l through the front contactsof relays F and F in series to a short insulated rail section a. A suitable source of connected between the lower rail A andthe insulated rail section a. With relays F and F ener ized as, shown the circuit ofma net- I is closed, so-that it The upper of these contacts closesthe operating circuit of the signal clear, while the, lower contact shunts the If atrain approaches in the direction ,indicatedby the arrow, it.

holds up its contacts.

H, holding it at either alternating or direct current, indicated by battery b', is

will begin to'pull down the voltage supplied by the transformer E to the track some time before it reaches this transformer, and when the voltage drops a predetermined amount, relay F will drop its contacts. .The distance between the train and the transformer, when this occurs, of factors,principally on the frequency of the current-,and consequently the impedance of the rails, transformer E The point at which the train is whenrelay F drops its contacts is immaterial in the present system, since these contactsare shunted by the lower contact of magnet I, so that the movement of relay F 2 to open circuit position produces no change in the circuit connections. remains at clear until the front wheels of the train reach the short insulated rail section a. At this instant magnet -I is shortcircuited and drops its contacts, thereby opening the actuating circuit. of signal H and allowing signal H. to go to danger. As the train passes off the insulated rail section, the. magnet I'does not again close its conslnce its circuit is now open at the contactsof relay F so that it cannot again close its contacts and clear the signal until relay F returns to the position shown in the drawing. This cannot occur, however, as

long as the train is-between the transformer and on the regulation of the.

The signal H will depend on a number 1 signal' circui-ts; tlon serves simply as by producing a second break in the circuit H clear until the'trainhas'passed sufficiently be ond transformer E for the voltage of this transformer .to rise enough to cause relay F topick up its contacts. The use, of the magnet I and the short insulated rail section thus makes the entrance'point-of the" block absolutely definite; so that a low frequency may be employed, if desired, for the a circuit-closing dev ce actu'atedby the train, and any other suitable circuit-closing device adapted to be actuated by a: passing train may be employed-in place of this insulated rail section. e

If a train should be near the centerbf the block, so'that both-relays 'F energized, and if a second train, approaching and finding the signal at danger, should.

. stopat the signal, and consequently close ture of relay F up',

to transformer E relay I, its. contacts when the first train left the:

I contacts of 2 relay "F -'w1llclear as soon as the first trainleaves the the second train close of transformer E ranged to control arelay-J, supplied from controlling device g 1 in the'windings f and f the armature of relay F down,

to. drop its contacts:

transformer E F would not pick ck, were it not/for the auxiliary contacts on relay F .Consequently'the signal H would not clear, and the second train might be needlessly-delayed. Withthe auxiliary however, the. signal H block, regardless of the presence of to the secondary terminals These-contacts are. ar-

any suitable source j and'arranged when energized to supply tothe track winding 1 Y of the relayF a current of the same frequency as thatsu-ppliedto thetrack by transformer'E [This current it taken from the secondary of transformer G the phase- I being excluded fromv this'circult, 'sothat the" necessary phasedi'ifere'nceis secured vbetween the currents of relay F With is energized, thereby energizingflrelay F? independently ofthe track. With the arena-.- relay J is short-- ':ircuited andinoperative. v y Y 'The sequence of operations issa's follows: A tramfentering the block causes'relay F 3 its contacts, thereby energiae' as the .train is closeto the relays,"-the relay' F will not pick up itscontacts but as the train passesthe relays and .draws near'to' will-pick up its relay F contact; and this .will be true whether or since the relay F the transformer E not a second trainhas reached the signal H,

s not now' dependent on' fore, as scenes the train passes transformer E? sufliciently for relay F contacts before relay" both hadztime-to open their contacts.

While'the-use of contacts controlled-by the The short insulated rail secit is obvious A: that thesecured in other ways.

and F are dea such railways having tween the relay J As thefitiain advances toward the relays,'.it' reaches a point 'where L relay F drop *ductive-ly' continuous forjall currents,

' fails at the ends is-of 5th current from the [source the block, andmean'sfor opening SaidshuHt for its current. 7 There;

to pick up its contacts, the circuit ofmagnet I will be closed,

and signalH will be cleared. I t will be understood that relay J andv magnet I are properly designed so that when relay F closesits contacts 'ma net l will close its 3 and relay F have.

magnet winding I ,..to shunt the contacts of relay yF V's '-a convenient "arrangement for securing. the, cooperation of, the 'magnet I with the track relays toncontrol'the signal, same resultmay be Consequently not desire'to: limit myself to the particular construction and arrangement of" parts here 'shown,but aim in the appended claims to' I coverall modifications which are within the scope of myiinvention.

-' {I do .not in this application make any claim'to ablock signal system for railways having both rails conductive'ly continuous for all currents, in ,whieh adjacent sources ofcurrentfor the track circuits are ofd fierent character and the relays are selectively responsive to current of one character-only,

claim'to a system for the relays arranged in sources, sincelthese nor .doI make any pairs between adjacent i 329,347, above referred ,to. i

v I at I claimas newcand desire to secure 100 byLetters- Patent of the-United States, is,--'-" 1. In a block signal system, in combma tion with a railway having both rails 'conductively continuous of "alternating current: connected-across the rails at theendsof the blocks, the currents relays connected'across the ra said sources, each responsive only-to current of a certain-elm.racter, a-signalcontrolled by each pair of relays, and means for rendering the relay responsive to current -matters forrnithesubject matter of my priorapplicatiomr serlal No, a

for; all-currents, sources a from adj acentsourcesgdifiering in character,

from the sourceat the entrance [to the block ineffective to operate the signal on vthe ap proach ofa train, until'the tl m. reaqheswa ffi'xed point in the track.

T 2. In 8-, block signal system, in combine tion with a railway havinggboth, rails onof alternating ,current con' ctedacr 2 blocks from adjacentsources vtrolledi by e;afcl 1 I shuntingicontactsjof he a thaentrancet ing contacts when a tra n reaches a' fixed point in thetrack.

-' lto;be denergjized byatrain at a fixed point; gin the track,- the winding of said ma et'ibelays connected across the rails ,in .pairs 1.b e l I tween said'sources, each resPonsiveohly to a current ofa certain character a-f signal 1 swindin'g-jinj serieswith contacts ;of hot re -Q ilays, contacts controlled. by said magnet shunting contacts of. the relay responding to current from. the source at the. entrance of the block, and 1 connections whereby. said I i 3.111 a bloclr-signalsysteni, coxnbinaif tion with a railway-ham .;both' rails ,condufctively continuous fora currents, sources relaysconnectedacross-the ra in pairs be :--'."tw een" said, sources,"each responsive 7 only to current "of acertain character,"a signal controlled i by each pair of; relays,f contacts hunting contacts. of the. relay' responsive 5 to current from the source at i the. entrance to the block, and; a .n agnet' normally holdin i.said shuntinggcontacts; closed and arrange Q to be deeliergized by a trainat'a fixedpoint "(in the-track} 5 f tion with ahrailway havmg'bothj rails con-- 9 riailsat the ends of the-Jblocks, ;the currents irom adjacent sources difierin in character, f .relaysconnectedacross the ra 1n palrs b'e-- jtweens'a d sources, each responsive 'only to troll d h each pair of relays, contacts .v 'shunting fc'ontact's of the relay responsive to 'f}: current .from the source at theentrance to "the.- block, and" a magnetnormally holding said shunting contacts closed and arran contacts. 1

,1 with arailway havin ;b0th rails conductwel cont nuous fora l-current's, sources of Y ,f alternating current connected across-the rails.

at; the ends of'the blocks,'the currents from lays connected acrosathe, rails in pairs be- I tween saidsources, each Tresponsive only to current of ajcertain character, 'a .signaha ,magnet controll ng sald, slgnal havm its energiz'ati'onof-"saidmagnet-by an approach;

' fing tr'ain unti-lithe train reaches a-fix'ed point.

in the track.

adjacent sonrcesgdifierin'g character, re-

magnet 'cor'itrollingsa 1d.'- signal." hav n 4.1a a block signal systeln, fifletmbina ductively continuous for all eurrents, sources of alternatm'g current connectedacross the.

cllfrrntof a'certain character a sign'al'c'onfe points of the blocks.

1 a distance. apart n'g'included in circuit withsaid s unting v 5. Ina block signal'system,incornbination 1 adjacent sources differing 'in character, -.r e-

winding" in series with contacts of bot relays, and means, for; preventing the de 6. a In ablock signal s aaaaaanaan at the'en ,s of the blocks, the currents from-f fear-33s a fixed point int e-tra'ck: a v R '73. Ina block signal system, the comloina- .tion'with a railway having both railsj com magnet is deener ized when atrain reaches ,ductively continuous for all currents, sources.

of alternating-current connected acrosstthe v rails at the ends; of the blocks, the currentsfrom adj acent's ources difi'ering ii -character,-

si alcontrollingmeans connected across therails at the point between said sources, a sig- I nalcontrolled thereby,ya-;normally energized .Inagnet coiiperating' withsaid means to control said signali ,and cqnnections whereby said'ma ems eenergiz'ed' only'byfla'train at a fix' poiiitin the track;

v 1- ,8; In comb'natio'n with'an electric railway havin' both rails conductively continuous for al currents, sources of current connected at intervals across the rails, thefc'urrents from/adjacent sourcesdiflerin in character ,from eachiother and from t e power-current, track relays connectedacross thezrails each responsive to current of one character only, block signals controlled by'said'relays, an means for definitely fining the entrance Q 9. In combinatlonwlth an electric-railway havin jboth 'railsconductively continuous for a currents, two souree'skoii current of diflerent character connected across-the rails a block :signal'for theportion'of-t e tracit betweensaid source's, sig- 7 nal-controlling nieans connected across; the rai1s-at,a point between said-sources and ary ranged to put said signal at danger upon a failure of current from either of said sources,

and means --f0r preventing said si a1 iron;

being ut'to danger by anapproac ingtrain until t e'train-reachesa .fixedrpoint; the

track;

way having, both rails conductively con- 1 tinuo u s" ,for all currents, two sources-of current offdifl'erent. character connected across the rails a distance apart, a normally clear block signal for thejportion offtrack between said'sources, two relays connected,"

across therrails atya point between said. sources each responsive :to' current of one a character only, and means coo crating with.

said'relays to control the sigma [arranged to The actuated by. a'train at a fiz'red po nt on the track. 3 v

1-1. In a block signal system, in combina- 'tio'nj with arailway liavingbothrailsconv ,ductiyelycontinuous for allcurrents,- sources of alternating current connected across the tween thesaid, sources,leach responsive to 'current frorn one of said'fsourcesionly, a

signal controlled by each pairof relays, and

ineans ,contrplled-by the relay-responsive to g IOQInjcOmbinatiQn witln an electric 2 rail- 1 05- current from the source at the exitend of the block for controlling the relay responsir'e to current from the source atthe entrance-end of the block.

12. In a block signal system, in combination with a railwayhaving both rails con ductively continuous for all currents, sources of alternating current connected across the rails at the ends of the blocks, the currents from adjacent sources (littering in character,

relays connected across the ails injpairs between the said sources, each responsive to current from one of said sources only, a

' signal controlled by each pair of relays, and

of the track-circuit current of the character to which it responds.

14. In a block signal system, in combination with a railway having both rails conductively continuous for all currents, sources of current of different character connected across the rails at the ends of the blocks, a signal,,and a pair of relays jointly controlling said signal, each relay having two tooperating; windings, one connected across the rails at a point between said sources, and the other supplied with current independently of the track-circuits, one of said relays being provided with back contacts arranged and connected to supply to the track winding of the other relay independently of the traclccircuits a current corresponding in character to that supplied to the track by one of said sources,

15. In a block signal system, in combination with a railway having both rails conductively continuous for all currents,sources of alternating current connected across the rails at intervals, a pair of track relays supplied with current trom the rails between two adjacent sources, each responding to current from one adjacent source only, a signal near one of said sources guarding the portion of track between said sources and controlled by said pair of relays, and means actuated by a train approaching the source near the signal for controlling the signal jointly with said pair of relays.

18. In a block signal system, in combination with a railway having both rails conductively continuous for all currents, sources of alternating current connected across the rails at intervals, a pair of track relays supplied with current from the rails between two adjacent sources, each responding to current from one adjacent source only, a signal near one of said sources guarding the portion of track between said sources and controlled by said pair of relays, and means cotiperating with said relays ,in the control of the signal for fixing the point reached by a car when the signal goes to danger.

h 17. In a block signal system, in combination with a railway having both rails conductively continuous for all currents, sources of alternating current connected across the rails at intervals, a pair of track relays supplied with current trom the rails between two adjacent sources, each responding to current from one adjacent source only, a signal near one of said sources guarding the portion of track between said sources and controlled by said pair of relays, contacts shunting the contacts of the relay responding to current from the source 'near the sig nal, and means for operating said contacts arranged. to be actuated by a train approaching said source.

18. In a block signal system, in combination with a railway having both rails conductively continuous for all currents, sources of alternating current connected across "the rails at intervals, a pair of track relays suplied with currentfrom rails between two adjacent sources, each responding to current from one adjacent source only, a signal near ne of said sources guarding the portion of track between said sources and controlled by said pair of relays, and a relay arranged to be actuated by a train approaching the source near the signal and controlling the signal jointly with said pair ofrelays.

191 In a block signal system, in combination with a railway having both rails c0n ductively continuous for all currents, sources of alternating current connected across the rails at intervals, a pair of track relays supplied with current from rails between two adjacent sources, each responding to current from one adjacent source only, a signal near one of said sources guarding the portion of track between said sources and controlled by said pair of relays, and a relay arranged to be actuated by a train approaching the source near the signal and controlling the movement of the signal to danger.

In witness whereof, I have hereunto set my hand this 7th day of June, 1907.

LAURENCE A. HAWKINS.

Witnesses 1 BENJAMIN B. HULL,

AZIARGARET E WOOLLEY. 

